Ophthalmic lens and process of making the same



Dec. 5, 1939. o. G. HAUSSMANN 2,182,537

OPHTHALMIC LENS AND PROCESS OF MAKING THE SAME Filed Oct. 15, 1957 fig 1 9 Fig.1]. J57 A? $29.15. Jig-J5 2/ If .15.

A7270 5'. Haussmazm g4 5% 4m I Patented Dec. 5, 1939 UNITE STATES OPHTHALMIC LENS AND' PROCESS OF MAKING THE SAME Otto G. Haussmann, Philadelphia, Pa,

Application October 15,

3 Claims.

This invention which is a continuation-inpart of my application Serial No. 37,235, filed August 21, 1935, relates to the making of ophthalmic lens With an elliptic reading segment, which ordinarily would have its long axis in a transverse meridian, but in special instances might have its long axis otherwise directed.

The general advantage of a lens with horizontal elliptical segment is to extend the reading field in the direction of the printed line, giving a range to the lateral roving of the eye, in reading, without the necessity ofturning the head; also, the avoidance to a large extent of the annoying doubling of images when looking downward, especially when walking down stairs.

One of the objects of the present invention is to provide a simplified and commercially feasible process for producing lenses of the class described.

Specifically, the object of the invention relates to the manufacture of a multi-focal lens with a button having an elliptical segment of flint glass, the segment extending through the button so as to appear in both surfaces thereof, and the wall, depthwise through the button, which demarks the flint from the crown glass of the button being of toric curvature. The advantages of having these walls of a toric curvature is that flint glass reading segments of different size and shape can be obtained by merely grinding away a portion of the surface of the button until the flint element will be of the desired size and then fusing it into a depression in a crown glass basic lens.

One of the objects of the invention is the possibility which it affords of carrying in stock a number of identical integrally fused buttons with flint glass reading segments, and adapting them for specific prescriptions by the grinding of the proper depression in a crown glass basic lens into which the button is to be fitted, and grinding the exposed surfaces after fusion with the basic lens to obtain the desired size and shape of the reading segment.

The objects of the invention include the lens as well as the process of making the same, and include also such other objects as may appear in the following disclosure.

In the drawing throughout the several figures of which the same characters of reference have been employed to designate identical parts:

Figure 1 is a plan View of the crown glass component of a button in which an elliptical aperture has been formed having a toric wall, following the principles of the invention;

1937, Serial No. 169,286

Figure 8 is a plan View of the crown glass component of the button having an aperture such as would be made by the tool shown in Figures 6 and 7;

Figure 9 is a section taken along the short axis of the elliptical aperture shown in Figure 8; Figure 10 is a similar view taken on the long axis;

Figure 11 is a cross section showing the flint core juxtaposed to the crown glass component of the button preparatory to fusing;

Figure 12 is a similar View showing the flint core fused;

Figure 13 is a section showing the button fused into a depression in the basic lens;

Figure 14 is a section similar to Figure 9, the button and basic lens being ground down-t0 a uniform contour;

Figure 15 is a plan view of the basic blank with a butt0n-receiving depression;

Figure 16 is a plan view of the finished lens; and

Figure 17 shows views in plan of several forms of ophthalmic lens which may be readily made by varying the extent and angularity of the final grinding.

In accordance with the present invention and referring in detail first to the group of Figures 1 to 5, inclusive, the numeral I represents the crown glass component of the button 2 which is ground through to form the elliptical aperture 3, the grinding tool being of the rotary type and being applied edgewise to the glass. It will be noted from Figures 1 and 2 that the walls of the elliptic aperture 3, in that form of the invention illustrated in Figure 1 are parallel at the ends of the short axis of the ellipse as indicated at 4 in Figures 1 and 2 and that they slope convergently downward with toric curvature at the ends of the long axis of the ellipse as indicated at 5 in Figures 1 and 3. The tool for grinding such a depression is illustrated in Figure 4 in which 6 is the rotating spindle, the tool being a wheel 1 having a peripheral grinding surface 8 which is at least the semi-circumference of a circle.

The aperture illustrated in Figure 1 would be produced by sinking the tool into the glass until the ends of the diameter 9 of the curved surface 8 have penetrated below the lower surface of the crown glass component I. The sides of the grinding tool would produce the parallel portions of the wall 4 while the circumferential arcuate portion of the tool indicated at It} in Figure will always produce convergence in the walls of the aperture at the ends of the long axis of the ellipse. This is an extreme depth of cut of the grinding tool. It is obvious that if it is not sunk to such a depth that the cross sectional diameter reaches the lower surface of the component I, the aperture will have a downwardly convergent wall all around.

The grinding surface of the tool may have any desired size and shape of transverse section within the range of toric curves, that is, curves described by the revolution of a conic section about an axis. The nature of the curve and the extent to which the grinding tool is made to penetrate the glass will modify the. shape of the depression.

The group of Figures 8 to 10, inclusive, illustrate a modified form of depression made with the grinding tool H illustrated in Figures 6 and '7, the grinding surface l2 of which is a tore having the characteristic of an ellipse. It will be observed from Figure 8 in which the numeral I represents the crown glass component of the button 2, that the elliptical aperture I3 is formed with downwardly convergent walls M at the ends of the short axis as illustrated in Figure 9, and that the walls l5 at the ends of the long axis also converge downwardly as illustrated in Figure 10,

In making the button, an aperture is formed entirely through the crown glass component, the plan aspect of which aperture is elliptical and the wall of which depthwise through the glass has the characteristics of any desired tore. This aperture may be produced in any suitable manner as by means of grinding tools such as are herein illustrated and have been described. A piece of flint glass I6 is then placed in juxtaposition to the aperture formed in the basic component of the button and the two are heated until fusion takes place, the more readily fusible flint glass entering the aperture and conforming to the walls thereof. An excess of flint glass is customarily provided which may spread over the top of the basic component I as shown at I! in Figure 12, but this is of no moment for this will be removed in the final grinding.

In making up a lens a basic blank E8 of crown glass is formed with a suitable depression l9. The lower face 20, Figure 12, of the basic component of the button together with the lower face 2| of the flint glass core which is exposed at the lower face of the basic component of the button are ground to the approximate curvature of the depression IS. The upper surface of the button is then ground away until the flint element is of the desired elliptical size and shape. The button is then placed in said depression and the basic lens blank 18 together with the bottom are subjected to the temperature of fusion at which the basic component I of the button if made of the same glass and same refractive index as the basic blank of the lens, merges homogeneously into the mass of the lens blank, the lower face 2| of the flint glass core l6 being fused and conforming to the shape of the depression I9. The upper side of the thus integrated lens is suitably ground away as indicated by the broken line 23 in Figure 13 until desired excess parts of the button have been removed and only the reading segment 22, Figure 16, remains. The wall of demarcation between the flint and crown glass, depthwise through the extent of the crown glass will have toric characteristics, and if the wall is left continuous all around in the grinding, the shape of the flint segment will be elliptical. If, however, the grinding tool is tilted so as to obliterate the wall of demarcation entirely, at one place, the flint segment will end at the periphery of the lens and its shape will be accordingly modified, as illustrated, by the shapes shown in the lenses a, b and c in Figure 17, in which the flint segments are shown at 24, 25 and 26.

One of the advantages of having the aperture, 3 or l3 formed with a toric wall depthwise through the basic component of the button is that such toric surfaces always converge downwardly at least in certain directions so that by grinding off only a little from the upper surface of the button, a small reading segmentis produced while by grinding to a greater depth the size of the segment is increased. Some eye glass wearers prefer a large reading segment and some a small one. By the present invention both of these desires can be satisfied from a stock of identical buttons made according to the principles of the present invention. To obtain the necessary diopter correction, it is essential merely to grind the depression in the basic lens blank to the correct curvature. A button from the stock of identical buttons and ground to produce the desired size, is then fused into this depression.

It is not essential to the invention that the basic component of the button be of the same refractive index as the basic lens blank. A trifocal lens with an elliptical reading segment and a surrounding segment of intermediate focal power may be formed with making the component I of the button of glass having a coefficient of refraction intermediate with respect to the optical powers of the basic lens blank I 8 and the flint core l6.

While I have in the above description disclosed what I believe to be a preferred and practical form of the invention, it will be understood to those skilled in the art that the details of construction and the technique of the process may be varied without transcending the principles of the invention as defined in the appended claims.

What I claim is:

1. Button for ophthalmic lens comprising, an integrally fused core extending through a surrounding portion, of glass having different respective refractive indices, that of the core being greater, said button being essentially thicker than the finished thickness to which it will be reduced by grinding, said core being elliptical in transverse sections, the depthwise boundary wall between the core and the surrounding glass having a toric curvature, such that said wall slopes more gradually at the ends of the long axis of the core than at the ends of the short axis, whereby, by grinding identical buttons to different depths from one or both faces of said buttons, segments are produced having reading fields of different sizes.

2. Process for producing a button for an ophthalmic lens comprising, forming through a basic mass of glass of relatively low refractive index, and which is essentially thicker than the eventual segment to be made from said button, an aperture elliptical in transverse sections, and the depthwise boundary wall of which is of toric curvature, and fusing a core of glass of relatively high refractive index in said aperture, the curvature of said boundary wall being such that said wall slopes more gradually at the ends of the long axis of the core than at the ends of the short axis, whereby, by grinding said button to difierent depths, from one or both faces of said button, a segment may be produced having a reading field the size of which is selectively determined.

3. Process for producing an ophthalmic lens comprising, forming a basic lens blank with a button-receiving depression of suitable curvature, taking a button of that type which comprises an integrally fused core extending through a surrounding portion, of glass having different respective refractive indices, that of the core being greater, said button being essentially thicker than the finished thickness of the segment to be made from it, said core being elliptical in transverse sections, and the depthwise boundary wall between the core and the surrounding glass having a toric curvature such that said wall slopes more gradually at the ends of the long axis of the core than at the ends of the short axis, and grinding away the surface of said button which is to contact the surface of the depression in the basic lens blank until the reading field constituted by the lower surface of the core has been enlarged to the desired size,'fusing the button to the surface of the depression in the basic lens blank, and grinding the exposed end of the button and the adjacent surface of the lens blank away until the reading field constituted by the exposed surface of the core is of the desired size.

I OTTO G. HAUSSMANN. 

